Duvall, Melvin R.
Ph.D. (Doctor of Philosophy)
Department of Biological Sciences
The conservation of endangered and threatened plant species plays an integral part of preserving biodiversity. Loss of habitat is one of the main reasons that plants become endangered or threatened. In Illinois much of the native habitat has been lost to the conversion of industry, agriculture and urban areas. The goals of this dissertation are to 1) determine where endangered and threatened species are finding habitats in relation to land use, 2) produce a robust phylogeny of endangered and threatened species of grasses and apply phylogenetic diversity analysis to better understand the plight of these species, and 3) use climate change predictions and phylogenetic diversity metrics to try to preserve biodiversity in the tallgrass prairie. First, I retrieved the number of endangered and threatened plant species per county for Illinois. I calculated the proportion of land cover per county for anthropogenic, non-anthropogenic, and protected areas. I modeled the distribution of state-listed endangered and threatened seed plants as a function of land cover and human population density. My study revealed that many endangered plant species are persisting in counties with high population densities that also have protected areas preserving habitats for the plants. Second, I studied the ecological and evolutionary roles of endangered and threatened grasses in Illinois. To avoid the disturbance of endangered and threatened populations, DNA was extracted from herbarium specimens. Next generation sequencing (NGS) techniques were used to sequence DNA of chloroplast genomes (plastomes). The extracted DNA successfully produced complete plastomes demonstrating that herbarium material is a practical source of DNA for genomic studies. The resulting phylogenomic tree was analyzed by phylogenetic diversity metrics. The results of the analyses confirmed my hypothesis that the phylogenomic distribution of endangered and threatened species of grasses in Illinois was phylogenetically clustered because closely related species would be vulnerable to the same threats and have similar requirements for survival. Third, I proposed a model to predict species loss and provide a pool of candidate species for assisted migration to supplement the plant community. Based on the principles of a reciprocal transplant common garden, I compared the composition of plant communities in Northern tallgrass prairies to Southern tallgrass prairies that are currently experiencing the projected climate conditions of the Northern area. From this comparison, I determined which species were likely to survive the projected conditions in the Northern area and which species in the Southern area were candidates for assisted migration. I identified 177 species of native plants that will be susceptible to extirpation from the Northern sites. I also identified a pool of species from the Southern area that would be candidates for assisted migration to fortify the Northern plant community. My analyses demonstrated that assisted migration has the potential to be a useful technique to supplement biodiversity.
Pischl, Phyllis H., "An investigation of Endangered and Threatened Plants Using Phylogenomics, Phylogenetic Metrics, and Geography to Prevent Species Loss" (2021). Graduate Research Theses & Dissertations. 7554.
Northern Illinois University
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